I know the engines have been refurbished and refitted.
Inspected and tested.

I am questioning if this is the first set of engines rechecked after the explosion or are they the last.

They should have been the first because there are the very next ones to be used. Unless they just found out what caused the explosion in the test and now want to check this set again for that problem.

The delay for this inspection should also have been set the day the explosion took place.
They did delay the early June launch already. At the time of the explosion they should have just said no more flights until each engine has been inspected and or tested.
This announcement this week would then not have been made.
Pretty much all they said this time was we are going to inspect this set of engines. And we are setting the next launch date for July. Unless…….

I;m questioning why this inspection wasn’t automatically done and why they waited until now to do it.
Did they find the reason for the first explosion(if so what was it)or are they just going through the motions to look good.

You are making incorrect assumptions about what Orbital has been doing in connection with these Russian engines.

All these Russian engines were inspected and refurbished prior to their installation in Antares. Thus, the engines that are in the Antares rocket scheduled for launch in July have already undergone the exact same tests that caused the engine in May to explode.

What has happened is that when they were testing that engine in May, something happened that caused it to blow up that had not occurred in any previous tests for identical engines. It appears that the investigation has figured out what went wrong, and they are simply being prudent by reinspecting the engines installed in Antares to make sure they don’t have this same problem.

What is not happening is Orbital doing “something that should have been done before.” It seems to me that this is an unfair criticism.

Or are they just now getting around to inspecting the engines and this is the first one inspected?

Maybe they finally found the real problem and just want to second check this set for the problem now that they know what to look for.

Scrubbing a launch to do something that should have been done before is not good.